fix: component port labels showing wrong name after editing blueprint

The label lookup in drawComponentGate read from gate.component (potentially
stale copy) while gateOutputCount read from state.customComponents (updated
definition), causing a mismatch — fewer ports but old outputIds, so the
first (deleted) output's label was shown instead of the surviving one.

Three fixes:
- renderer: use customComponents as authoritative source for label lookup
- saveLoad: re-link gate.component refs to customComponents after loading
- components: update existing instances even when a "new" component
  overwrites an existing definition with the same name

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

js/renderer.js

@@ -325,8 +325,10 @@ function drawComponentGate(gate) {
     ctx.fillStyle = '#444';
     ctx.fillText(getGateLabel(gate), gate.x + w / 2, gate.y + h - 6);
 
-    // Get port labels from the component definition
-    const comp = gate.component;
+    // Get port labels from the authoritative component definition (customComponents)
+    // This must match the source used by gateOutputCount/gateInputCount for port counts
+    const compId = gate.type.substring(10);
+    const comp = state.customComponents?.[compId] || gate.component;
     const inputLabels = [];
     const outputLabels = [];
     if (comp) {